Behind The Head Shoulder Press
The behind the neck shoulder press takes external rotation of the shoulder to it's highest level.
The behind the head shoulder press, just like the behind the head lat pulldown involves externally rotating your shoulders to maintain the correct position while lifting, this places your shoulders in an extremely fragile position.
While in an externally rotated position your rotator cuffs cannot stabilize the joint and supporting muscle correctly, leaving you at risk to injury to connective tissue too.
When performed with an olympic barbell loaded with weight this is just asking for an injury.
Upright Barbell Row
The upright row, a favourite of many gym-goers for building both the traps and shoulders.
This is without a doubt the #1 exercise to avoid like the plague.
Correct form of the upright row requires internal rotation of the shoulders...
Overloading your shoulders while they are internally rotated with heavy weight while attempting to raise them upward impinges a tendon in the shoulder .
The result? Unnecessary wear and tear on your tendon - potentially leading to snapping or further injury.
"But SJ, aren't sit-ups the best ab exercise out there?!"
Excessive stress on the lower back with not enough abdominal activation.
The abdominal activation from a sit-up is purely isometric - the hip flexors pull and the abdominals flex in their position.
The leg raise is a far superior exercise for the abs, check out my complete guide on leg raise progression from the floor all the way to the window wiper right here.
Particularly when performed quick and explosively, the sit-up places a ton of the power and speed you're utilizing to perform the movement straight to your lower back.
The movement, which as I mentioned is primarily through the hip flexors transfers that energy directly to your lower back via the spine, not good.